JPS63141890A - Exhaust controller for motorcycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust control device applied to a motorcycle having an exhaust control valve provided in the middle of an exhaust system.

(Background of the Invention) It is known that in 4-stroke engines, 2-stroke engines, etc., exhaust gas is intermittently guided into the exhaust pipe by opening and closing the exhaust valve, causing an inertial effect and a pulsation effect of the exhaust gas in the exhaust pipe. . These effects (referred to as dynamic effects) vary depending on engine speed. Therefore, if this dynamic effect is maximized to increase the volumetric efficiency at the rotational speed, the dynamic effect acts in the opposite direction at other rotational speeds, resulting in a significant decrease in the volumetric efficiency. Therefore, if the exhaust system specifications (exhaust pipe length, exhaust pipe diameter, etc.) are set so that this dynamic effect is optimal in the high speed range, the torque will significantly decrease (torque trough) in the medium speed range. There was a problem that occurred.

Therefore, an exhaust H2N valve is installed near the opening end of the exhaust pipe to the expansion chamber to change the exhaust flow path surface, reducing the flow path area in the rotation speed range where volumetric efficiency decreases, and reducing the flow path area in other rotation speed ranges. The idea is to increase the amount.

Furthermore, in a multi-cylinder engine, if the downstream sides of the exhaust pipes are merged in an expansion chamber, the volumetric efficiency and torque may decrease due to exhaust interference between the cylinders. Therefore, it has been considered to provide an exhaust control valve for each exhaust pipe and close this control valve in a rotational speed range where the adverse effects of exhaust interference occur to reduce the exhaust flow path area.

It is also being considered to improve combustion by controlling the back pressure in the exhaust pipe, and to control exhaust components by controlling self-EGR (exhaust gas recirculation).

As described above, it is conceivable to provide an exhaust pipe with an exhaust control valve that changes the exhaust flow path area for various purposes such as improving volumetric efficiency, improving combustion, and controlling exhaust components.

However, especially in the exhaust system of a motorcycle, a long exhaust system is usually installed in the front and back, extending from the front of the engine, passing below the engine, and extending to the rear of the vehicle body. Therefore, if a relatively heavy exhaust control valve is interposed in the middle of the exhaust system, there is a problem that the exhaust system becomes unstable and tends to vibrate.

Further, when the exhaust pipe is directly connected to the exhaust control valve, there is also the problem that it is difficult to maintain a high degree of relative positional accuracy between the exhaust pipe and the exhaust control valve, resulting in poor productivity.

(Purpose of the Invention) The present invention has been made in view of the above circumstances, and provides a system that, when an exhaust control valve is provided in the exhaust system of a motorcycle, improves the stability of the exhaust system, suppresses vibration well, and improves the exhaust system. It is an object of the present invention to provide an exhaust control device for a motorcycle in which relative positioning accuracy between a pipe and an exhaust control valve is significantly improved and ease of assembly is improved.

(Structure of the Invention) According to the present invention, the object is to connect the exhaust pipe led from the front of the engine mounted near the center of the vehicle body to the bottom of the engine to the exhaust muffler at the rear of the vehicle body through an exhaust control valve and an expansion chamber. In the motorcycle equipped with an exhaust system connected to the exhaust control valve, a branch pipe section connected to the exhaust pipe is integrally molded on the body of the exhaust control valve, and the upstream end of the exhaust pipe is connected to the engine and the exhaust muffler. The exhaust system is achieved by fixing the exhaust control valve body to the vehicle body respectively.

(Example) Fig. 1 is a partially sectional plan view of an exhaust control valve assembly according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line II of the same;
Figure 3 is also a view in the direction of the ■ arrow, Figures 4 and 5 are a sectional view taken along the IT-IV line and an end view taken along the line v-v in Figure 1, and Figure 6 is a motorcycle using this exhaust control valve. FIG. 7 is a plan view of the exhaust system, and FIG. 8 is a side view of a motorcycle using this exhaust system.

In Fig. 6.8, the symbol lO is a 4-stroke, 4-cylinder engine, which is mounted near the center of the vehicle body. This engine IO has a cylinder 14 extending diagonally upward and forward from a crankcase 12. The exhaust system consists of four exhaust pipes 16 extending from the front of the cylinder 14 to the bottom of the crankcase 12.
(16a to 16d, see FIG. 7) are connected to the rear end of the exhaust pipe 16 and collect the exhaust gas from each exhaust pipe 16 into an exhaust muffler 1.
and an exhaust control valve assembly 20 leading to 8.

As shown in FIG. 1, the body 22 of the exhaust control valve assembly 20 includes branch pipe portions 24 (24a to 24d) connected to each of the four exhaust pipes 16 and forming an exhaust pipe together with the exhaust pipes 16.
And downstream of this branch pipe part 24 (11 opening @ 16A-16
The 0 branch pipe part 24 is equipped with an expansion chamber 26 with an opening at 0, and one collecting pipe part 28, which are integrally cast from stainless steel. As shown in FIG. 2 , it is formed to have a circular cross section and is connected to each exhaust pipe 16 . Further, the downstream opening ends 16A to 1 of the branch pipe portion 24
60 has a vertically elongated rectangular opening shape as shown in FIG. 4, and is opened in parallel with the expansion chamber 26. As shown in FIG. As shown in FIG. 5, the branch pipe portions 24 are arranged so that their front ends form an inverted trapezoid, so that appropriate spacing is created between the branch pipes, thereby improving welding workability with the exhaust pipe 16. Said silencer 1
8 is detachably connected to the collecting pipe section 28.

28 is a crank-shaped valve body (Fig. 1), and this valve body 2
Both ends of the expansion chamber 8 are rotatably supported on the left and right walls of the expansion chamber 26 behind the open ends 16A to 180, and the intermediate portion 30 thereof is formed to have an arcuate cross section. Circular openings are formed in the left and right walls of the expansion chamber 26, and these openings are closed by bearing plates 32, 34.

The shafts 28a and 28b at both ends of the valve body 28 are respectively connected to the bearing plates 3.
2.34, one shaft portion 28b projects outward through the bearing plate 34, and a pulley 36 is fixed to this projecting end. The intermediate portion 30 is located at the downstream opening of the branch pipe portion 24, that is, the downstream GL opening end 16A to 160 of the exhaust pipe 16.
is facing. Note that the outer circumferential surface of the intermediate portion 30 and the downstream opening end 16A-160 of the exhaust pipe 16 are formed in the shape of a circular arc centered on the rotation center of the valve body 28, as shown in FIG. 2.3. close to each other. The exhaust control valve 20A is formed by the valve body 28, the downstream opening end 16A-160, the vicinity of the center of the body 22 surrounding these, and the bearing plate 32,34.

The pulley 36 is rotated by a servo motor (both not shown) via a wire in accordance with the rotational speed of the engine 10, and the exhaust control valve 20A is closed in the low to medium speed range of the engine lO and opened at high speed. controlled.

In this way, the exhaust pipe 16. This exhaust system, which is formed by the exhaust control valve assembly 20, the exhaust muffler 18, and the like, is formed into a substantially U-shape when viewed from the side, and its front upper end, that is, the upper end of the exhaust pipe 16, is fixed to the exhaust port of the engine 10. Further, the rear part of this exhaust system, that is, the exhaust muffler 18 is fixed to the lower end of a stay 40a (FIG. 8) fixed to the vehicle body frame 40.

The exhaust control valve assembly 20 is attached to the lowest position near the center of the exhaust system, that is, the body 22 is attached to the vehicle body frame 40 as shown in FIGS. 6 and 7. That is, the vehicle body frame 40 includes a pair of left and right hanging parts 42 (only one shown) extending downward along the rear part of the engine IO, and a bracket 46 is fixed to a cross member 44 that connects the rain hanging parts 42. A link 48 and a hanging plate 50 are collinear with this bracket 46, and a bracket 52 fixed to the body 22 is fixed to the lower end of this hanging plate 50.

In Fig. 6, 54 is a rear seam, the front end of which is pivotally supported by the hanging part 42 of the vehicle body frame 40, and the rear wheel 56 is attached to the rear end (Fig. 8). It is connected to the rear arm 54 by a pair of left and right links 58, 58 (FIG. 7). In addition, at the rotating end of the link 48, there is a support arm 6 on which the lower end of a shock absorber (not shown) is pivotally supported.
0 is provided protrudingly.

In FIG. 8, 62 is a front wheel, 64 is a steering wheel, 66 is a fuel tank, and 68 is a driver's seat.

Therefore, the diameter and length of the exhaust pipe 16 are determined by the engine 10.
When the volumetric efficiency is set to be high in the high speed range, the exhaust control valve 20A is driven by a servo motor so as to close in the low to medium speed range and open in the high speed range.

A positive pressure wave caused by the opening of the exhaust valve of the engine 1O propagates inside the exhaust pipe 16 at the speed of sound, and a negative pressure wave generated by the rapid expansion at the open ends 16A to 16D propagates inside the exhaust pipe 16 at the speed of sound.
propagates in the opposite direction at the speed of sound and returns to the exhaust valve of the engine 10. If the exhaust control valve 20A located near this open position @168 to 160 is closed, the positive pressure wave caused by the opening of the exhaust valve will be reflected by this exhaust control valve 20A, and the positive pressure wave will move at the speed of sound to the exhaust valve. Therefore, the exhaust flow path area is reduced to 17
2, the sum of the negative pressure wave generated by the open end of the exhaust pipe and returned and the positive pressure wave reflected by the exhaust control valve 2OA becomes zero. At this time, the pulsation effect is canceled out, and a decrease in volumetric efficiency (occurrence of torque valley) in the medium speed range can be suppressed.

Furthermore, when this exhaust control valve 20A is used for the purpose of preventing torque reduction due to exhaust interference between cylinders, the exhaust control valve 20A is
Just close A. In addition, in the low speed range, this exhaust control valve 20A
When closing, the usable part of the exhaust control valve 20A is one that reduces the exhaust flow path area by about 70 to 90% to about 30 to 10%.

In the above embodiment, not only the body of the exhaust control valve 20A and the branch pipe portion 24 but also the expansion chamber 24 are integrally formed with the body 22 of the exhaust control valve assembly 20 by °casting. However, the present invention also includes a configuration in which the expansion chamber is separate.

Furthermore, in this embodiment, the four exhaust pipes 16 are assembled in the expansion chamber 24, but the present invention also includes one in which one exhaust pipe is connected to the expansion chamber, and in this case, the branch pipe section is one pipe. will be formed.

Note that fixing the exhaust system to the engine 10 or the vehicle body frame 40 includes fixing using the tensile force of a spring or via a rubber damper.

(Effects of the Invention) As described above, the present invention fixes the upstream end of the exhaust pipe at the front of the exhaust system to the engine, and the exhaust muffler at the rear of the exhaust system to the vehicle body. The body of the exhaust control valve, which is located near a low position, is fixed to the vehicle body. That is, the front and rear parts of an exhaust system that is long in the longitudinal direction are fixed to the engine and the vehicle body, while a heavy exhaust control valve is placed near the center of the exhaust system and is fixed to the vehicle body.

Therefore, vibrations in the left-right direction of the exhaust system are well suppressed near the center, and the stability of the exhaust system is improved. Furthermore, since the branch pipe part is integrally molded into the body of this exhaust control valve by PJ construction, the relative positional accuracy of the branch pipe part and the exhaust control valve, which essentially form a part of the exhaust pipe, is determined by the casting precision. As a result, the positioning accuracy of both is improved, and the assembly accuracy is also improved.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional plan view of an exhaust control valve which is an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ll-H, Fig. 3 is also a view in the direction of the ■ arrow, and Figs. Figure 5 shows the JT in Figure 1.
-TV sectional view and V-v line end view, Fig. 6 is a side view of the exhaust system of a motorcycle using this exhaust control valve, Fig. 7 is also a plan view, and Fig. 8 is this exhaust system. FIG. DESCRIPTION OF SYMBOLS 10... Engine, 16... Exhaust pipe, 18... Exhaust muffler, 20... Exhaust control valve assembly1. 20A... Exhaust control valve, 22... Body, 24... Branch pipe portion, 26... Expansion chamber.

Claims (2)

[Claims] (1) In a motorcycle equipped with an exhaust system in which an exhaust pipe led from the front of the engine mounted near the center of the vehicle body to the bottom of the engine is connected to an exhaust muffler at the rear of the vehicle body via an exhaust control valve and an expansion chamber, A branch pipe section connected to the exhaust pipe is integrally formed on the body of the exhaust control valve by casting, and the upstream end of the exhaust pipe is fixed to the engine and the exhaust muffler is fixed to the vehicle body, while the exhaust control valve is connected to the exhaust pipe. An exhaust control device for a motorcycle, characterized in that a valve body is disposed near the lowest position of the exhaust system and fixed to the vehicle body. (2) The exhaust control device for a motorcycle according to claim 1, wherein the branch pipe portion and the expansion chamber are integrally formed on the body of the exhaust control valve by casting.